Materials
Dimethyl-1,2-benzenedicarboxylate, octane, n -propanol, andp -hydroxybenzaldehyde were provided from Aladdin, China. Ethyl
acetate, ethanol, anhydrous sodium
sulfate, copper sulfate, ferrous sulfate, zinc sulfate and magnesium
sulfate were purchased from Tianjin
Damao Chemical Reagent Factory, China. Sodium lignosulfonate and alkali
lignin were supplied by Sigma-Aldrich, China.
Organosolv lignin was obtained
according to our previous study.26 Briefly, 10.0 g
biomass feedstock (bagasse, poplar, bamboo or miscanthus powers), 1.2 g
concentrated H2SO4 (Guangzhou Chemical
Reagent Factory, China) and 150 mL 80% ethanol solution were placed
into a 250 mL stainless autoclave and heated to 393 K at a stirring
speed of 600 rpm. After 4 h, the autoclave was cooled rapidly under
flowing water. Then, the reaction mixture was filtered, the filtrate was
added into 500 mL deionized water for precipitating lignin. The solid
(organosolv lignin) obtained by filtration was then dried under vacuum
at 313 K for 12 h before use.